The bubble memory device comprises a bubble chip which is a memory element, a coil for generating a revolving magnetic field, a magnet for generating a biased magnetic field, and a shield for protecting the device from magnetic disturbance. This magnetic memory device is housed within a bubble cassette and the bubble cassette is inserted into the holder of the main apparatus. The bubble memory device is actuated by a control circuit comprising a bubble drive circuit, a writing circuit, a reading circuit, and a power circuit in the main apparatus. The bubble memory device housed within the bubble cassette is electrically connected to the control circuit within the main apparatus by the contacts of the bubble cassette, which contacts are connected to the contacts of the holder when the bubble cassette is inserted into the main apparatus. In the prior art cassette-type magnetic-bubble memory apparatus, current is introduced into the bubble memory device at the same time that a connection is made between the contacts of the cassette and the contacts of the holder, and is interrupted at the same time that the contacts of the cassette are disconnected from the contacts of the holder. Electric noise is generated at the point of contact between the contacts of the cassette and the contacts of the holder when they are connected and when they are disconnected. In the prior art apparatus, electric noise generated at the contact is introduced into the bubble memory device, thereby causing part of the stored data to be destroyed, causing the contact to be contaminated by the minor discharge at the contact and in turn causing degradation of the reliability of the memory.